Many construction, road building and other activities utilize compactor machines to compact material such as soil, asphalt, etc. and increase the density of the material for load bearing purposes. Compaction is also used for reducing material volume, as in the case of landfill trash. Conventional wisdom is to pass a compactor uniformly across a work area until the work material has been increased in density to a sufficient degree. While a uniform coverage approach is simple and straightforward, it has certain drawbacks.
Material within different regions of a work area will often tend to compact non-uniformly. In other words, for a given number of passes with a compactor there may be variation in the relative increase in density of the material among different regions of a work area. As a result, where uniform coverage is used certain areas may be under-compacted, certain areas may be over-compacted or the project may require an excessive amount of time. Expenses associated with operating construction machinery such as compactors can therefore often be high due to wasted effort by the compactor machine and necessary remediation where compaction does not occur as intended. In recent years, a variety of strategies have been proposed for improving compactor efficiency, such as systems which measure the density of compacted material and other strategies where the response of material to compaction in real time is monitored. While certain of these techniques have shown promise, there remains room for improvement.
It is common at construction sites for compaction specifications to be provided to a construction manager or contractor. In particular, a relative compaction state or minimum compaction value, minimum number of compactor passes, and other factors may be specified. There may be a number of different ways in which a work area can be compacted to satisfy the compaction specifications. For example, the entire work area might be compacted to within 90% of a specified minimum compaction value. Alternatively, a portion of the work area could be compacted to 100% of the specified minimum compaction value, whereas another portion might be compacted to a lesser degree of compaction. Still other combinations of compaction minimum value, compactor coverage, etc., can be imagined, and to a certain extent the manner in which specifications are met may be based on agreements between the contractor and the client. Department of Transportation agencies also commonly specify certain compaction state and/or compactor coverage requirements.
As mentioned above, improved sensing and control strategies have been proposed for operating compaction machinery in recent years, but still exhibit certain shortcomings. One problem in particular is that known systems often do not take into account the possibility of meeting compaction specifications by selecting one of multiple possible ways in which a machine system can be operated or navigated to compact a work area. In other words, while known systems might allow compaction of a work area to satisfy specifications more efficiently than relying simply on uniform coverage or operator judgment, these known strategies do not actually provide for calculation or estimation of the most efficient way to do so. Commonly owned U.S. patent application Ser. No. 11/517,065 to Congdon et al, filed Sep. 7, 2006, for example, discloses a concept where aberrant compaction response of a material is detected. The strategy of Congdon et al. promises significant efficiency improvements, as fruitless work on aberrantly responding material is avoided, but is not specifically directed to compacting non-aberrant material in an efficient manner.
The present disclosure is directed to one or more of the problems or shortcomings set forth above.